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Body Mass Index[edit | edit source]

(ie. (kg/m)²)

Classification of weight in adults[edit | edit source]

Classification BMI
Underweight <18.5
Normal 18.5-24.9
Class I Obese 30-34.9
Class II Obese 35 - 39.9
Class III Obese >40
  • waist circumference (not waist to hip ratio) can be added to increase the specificity of the BMI. Those at high risk are:
    • Men > 102 cm
    • Women > 88 cm
  • There is a U shaped relationship between BMI and mortality, with those over and underweight showing an increase in mortality

Epidemiology[edit | edit source]

  • Prevelence of obesity is > 14% (Canada)
  • There has been a doubling of childhood obesity in North America over the last 20 years

Assessment[edit | edit source]

  • Calculate BMI and waist circumference
  • Ask about comorbidities
    • Coronary artery disease
    • Hypertension
    • Smoking
    • Lipid profile
    • diabetes
    • Sleep apnea
    • Osteoarthritis
    • Gallstones
  • Assess motivation for weight loss and any surrounding support or obstacles
  • Examine past attempts and assess for efficacy
  • physical exam and investigations are based on specific patient complaints

Management[edit | edit source]

Weight Loss[edit | edit source]


  • BMI>30
  • BMI 25-29.9 or high waist circumference and 2 risk factors
  • weight loss is not to exceed 1kg/week with an initial goal of 10% loss in 6 months.

Weight Prevention[edit | edit source]

  • BMI 25-29.9 and less than 2 risk factors

Dietary Therapy[edit | edit source]

  • women: 1000-1200kcal/day
  • men: 1200-1600kcal/day
  • reduce usual intake by:
    • Obese: 500-1000kcal/day
    • Overweight: 300-500kcal/day
  • these reduction will result in a loss of 1kg/week

Temporary and/or drastic diets do not generally lead to long term weight loss. By reducing the caloric intake suddenly, the body will enter a "starvation mode" and losing fat will be more difficult.[factual?]

What most people who are obese need is a "permanent" change in their eating habits. Progressive substitution of bad products with healthy products will help reduce the shock from a sudden change in their eating style. A reduction of calories about 10% (maximum 20%) of their original caloric intake should do.[factual?]

Behavioural therapy[edit | edit source]

  • involve patients in goal setting
  • self monitor for dietary intake and exercise
  • reward when goals are acheived (not with food though)
  • dietary behaviour: eat slower, use smaller plates
  • modify environmental cues that prompt undesired eating

Pharmacotherapy[edit | edit source]

  • use if lifestyle changes do no work after 6 months
  • appropriate if BMI > 30 or >27 with co-morbidities/risk factors
  • sibutramine
    • appetite suppresant
    • inhibits norepinephrine and seretonin reuptake
    • side effects: increased BP, tachycardia
  • orlistat
    • reduces GI fat absorption
    • side effects: reduction in fat soluable vitamins, stool leakage diarrhea
  • ezetimibe
    • cholesterol absorption inhibitor
    • side effects:arthralgias, back pain, diarrhea

Surgery[edit | edit source]

  • for severe obesity
  • "stomach stapling", a bariatric procedure

References[edit | edit source]

Toronto Notes 2005